The biosynthesis, chemistry and interaction with trace elements of keratinoid proteins in mammalian spermatozoa are being studied, mainly in the rat. In addition, some effort is being made to understand the mechanisms by which the -S-S- linked structures containing these proteins are dissolved within the egg. The major divalent cation interacting with these proteins is Zn. The role of this mineral element in the assembly and maturation of keratinous structures is being evaluated by investigating its relative content in the various keratins as a function of maturation and the mechansims of its association with the -SH-containing proteins during biosynthesis. BIBLIOGRAPHIC REFERENCES: Calvin, H.I. and Temple-Smith, P. Subfractionation of -S-S- linked elements in rat sperm heads. J. Cell Biol. 67:53a, 1975. Calvin, H.I. Isolation and subfractionation of mammalian sperm heads and tails. Methods in Cell Biology 13:85-104, 1976.